By Thursday morning, the fire was mostly brought under control, although firefighters were still on the scene.
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Some tenants said there were no smoke alarms going off when the fire began and spread through the building.
The blaze quickly burned through the roof of the large Gregory Avenue apartment building in Passaic shortly after 8:45 p.m.
The flames started on the upper floors of the building in a wing overlooking the Broadway side and spread across a connecting area to a second wing. Portions of the roof have collapsed. The building houses 60 apartments.
Two firefighters suffered injuries. They were taken to St. Joseph's Regional Medical Center in Paterson. A portion of a ceiling fell on one, while another suffered burns to the neck.
The building was evacuated. None of the hundreds of residents evacuated were injured. Passaic officials estimated between 300 and 400 people lived in the building.
BREAKING VIDEO: 4th Alarm at 290 Gregory Ave in Passaic City, NJ. Credit: Mike Thomasey pic.twitter.com/ytLBJqjenC— N. Jerzy Fire Alert (@NJerzyFireAlert) October 22, 2015
BREAKING VIDEO: 4th Alarm at 290 Gregory Ave in Passaic City, NJ. Credit: Mike Thomasey pic.twitter.com/Y6mDThX5jc— N. Jerzy Fire Alert (@NJerzyFireAlert) October 22, 2015
"My thoughts and prayers go out to all those impacted by the tragic fire on Gregory Avenue," said Passaic Mayor Alex Blanco.
The cause of the fire is undetermined.
The Red Cross set up a reception area for the displaced.